TITLE:   GCN CIRCULAR
NUMBER:  10716
SUBJECT: GRB 100504A: Swift-BAT refined analysis
DATE:    10/05/05 04:01:19 GMT
FROM:    Scott Barthelmy at NASA/GSFC  <scott@lheamail.gsfc.nasa.gov>

D. M. Palmer (LANL), S. D. Barthelmy (GSFC), W. H. Baumgartner (GSFC/UMBC),
J. R. Cummings (GSFC/UMBC), N. Gehrels (GSFC), H. A. Krimm (GSFC/USRA),
J. Mao (INAF-OAB), C. B. Markwardt (GSFC/UMD), T. Sakamoto (GSFC/UMBC),
M. Stamatikos (GSFC/ORAU), J. Tueller (GSFC), T. N. Ukwatta (GWU)
(i.e. the Swift-BAT team):
 
Using the data set from T-239 to T+363 sec from the recent telemetry downlink,
we report further analysis of BAT GRB 100504A (trigger #421124)
(Mao, et al., GCN Circ. 10712).  The BAT ground-calculated position is
RA, Dec = 255.575, -35.590 deg, which is 
   RA(J2000)  =  17h 02m 18.1s 
   Dec(J2000) = -35d 35' 23.0" 
with an uncertainty of 1.0 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 92%.
 
The mask-weighted light curve shows two overlapping peaks followed by a
weak third peak, starting at ~T-10 sec, peaking at T+0, T+8, and ~T+90 sec,
and ending at ~T+100 sec.  T90 (15-350 keV) is 97.3 +- 7.3 sec
(estimated error including systematics).
 
The time-averaged spectrum from T-9.7 to T+102.2 sec is best fit by a simple
power-law model.  The power law index of the time-averaged spectrum is
1.76 +- 0.10.  The fluence in the 15-150 keV band is 2.4 +- 0.1 x 10^-6 erg/cm2.
The 1-sec peak photon flux measured from T+7.60 sec in the 15-150 keV band
is 1.7 +- 0.2 ph/cm2/sec.  All the quoted errors are at the 90% confidence
level. 
 
The results of the batgrbproduct analysis are available at
http://gcn.gsfc.nasa.gov/notices_s/421124/BA/